The present invention relates to a cured unsaturated polyester resin or vinyl ester resin containing fluorine-containing groups oriented on its surface, which is obtained by curing an unsaturated polyester resin or vinyl ester resin together with a block copolymer consisting of a polymer portion having fluorine-containing groups and a polymer portion compatible with the unsaturated polyester resin or vinyl ester resin.
Unsaturated polyester resin or vinyl ester resin has ester linkages in its molecule, and hence the resin has high affinity to water and hence has high water absorption. Therefore, shaped articles of the unsaturated polyester resin or vinyl ester resin are poor in water resistance and weather resistance due to the hydrolysis of the ester linkages.
Unsaturated polyester resin and vinyl ester resin are used as a matrix of reinforced plastic articles and have strength and beautiful appearance. Therefore, the resins are widely used in bathtub, automotive body, ship, computer housing and the like. However, unsaturated polyester resin or vinyl ester resin used in the automotive body or bathtub is deteriorated due to the adhesion of fur or to the hydrolysis of the resin caused by the action of water for a long period of time. The resin used in the automotive body or computer housing is stained due to the adhesion of oil, pitch, aqueous and oily writing materials, adhesion tape and the like.
There have been proposed several methods in order to solve the above described various problems. For example, when the hardened degree of a cured unsaturated polyester resin or vinyl ester resin is increased in order to decrease the remaining monomer (for example, styrene) into a very small amount, the water resistance, weather resistance and corrosion resistance of the resin are improved. This method is an ordinarily used method.
Further, Reinforced Plastics (Japan), Vol. 26, pages 425-434 (1980) discloses that a reinforced plastic corrugated plate consisting of an unsaturated polyester resin and glass fibers is overlaid with a fluorine-containing polymer film to improve the weather resistance of the plate.
However, it is commonly known that the water resistance, weather resistance and stain resistance of unsaturated polyester resin or vinyl ester resin depend upon the chemical structure of the resin itself. Accordingly, merely the increasing of the hardened degree of the resin cannot serve to improve significantly the water resistance, weather resistance, stain resistance and the like of these resins.
On the contrary, the above described method of overlaying a fluorine-containing polymer film on an unsaturated polyester resin or vinyl ester resin can give properties, such as water resistance, weather resistance, stain resistance, anti-block property, water repellency, oil repellency and the like, to the resin. The reason is that the bonding force of a fluorine atom to a carbon atom in the fluorine-containing polymer is high, and the polarizability of fluorine atom is small, and accordingly the cohesive force between fluorine-containing polymer molecules is small and further the surface tension of the fluorine-containing polymer is very low.
However, the overlaying method has a serious problem in that a fluorine-containing polymer film overlaid on an unsaturated polyester resin or vinyl ester resin is not so strongly bonded to the resin. That is, the fluorine-containing polymer film is poorly adhered to the unsaturated polyester resin or vinyl ester resin, and the fluorine-containing polymer film may be peeled off from the unsaturated polyester resin or vinyl ester resin during the use for a long period of time of the resin overlaid with the polymer film, and the above described properties of the resin overlaid with the polymer film are lost.
Further, the poor adhesion of the fluorine-containing polymer film to the unsaturated polyester resin or vinyl ester resin causes a high fraction of defective products in the production of unsaturated polyester resins or vinyl ester resins overlaid with the fluorine-containing polymer film.
Conventional methods for improving the water resistance, weather resistance, stain resistance and the like of unsaturated polyester resin or vinyl ester resin by the use of a fluorine-containing polymer still have the above described various drawbacks.
The inventors have made various investigations in order to improve the water resistance, weather resistance, stain resistance, water repellency, oil repellency and the like of unsaturated polyester resin or vinyl ester resin, and have ascertained that the above described drawbacks of conventional methods can be solved by a method, wherein an unsaturated polyester resin or vinyl ester resin is cured together with a block copolymer consisting of a polymer portion having fluorine-containing groups and a polymer portion compatible with the unsaturated polyester resin or vinyl ester resin, to orient the polymer portion having fluorine-containing groups on the surface of the resin. As the result, the inventors have accomplished the present invention.